Book excerpt: What does federalism have to do with the political struggle between conservatives and progressives over economic policy? How do economic theories of fiscal federalism influence European, North American, and global forms of governance? In the first comprehensive account of the left-right politics of multilevel governance across federal, regional, and global levels, Adam Harmes identifies both free-market and interventionist political projects related to fiscal federalism. Harmes argues that these political projects and the interests that promote them explain a diverse range of phenomena across national contexts, across levels of governance, and over time. This includes the left-right dynamics of US and Canadian federalism, the free-market origins of British euroscepticism and the Brexit vote, the complex politics behind the NAFTA renegotiations, and the emergence of both populist and progressive challenges to global free trade. A highly accessible outline of fiscal federalism theory, The Politics of Fiscal Federalism also expands upon the broader value and policy differences between neoliberal, classical liberal, and Keynesian welfare economics on issues such as the role of the state, subnational and global trade, economic nationalism, and monetary integration. This original and innovative work demonstrates that a political economy approach is essential to the study of federalism, and why federalism and multilevel governance is a critical area of study for political economists.